Competitive and non-competitive effects of neonate visual restriction in cats will be examined. First, various conditions of binocular visual restriction will be used to create non-competitive deprivation effects during visual system development. In these conditions spatial and/or temporal factors of visual input will be differentially manipulated to determine whether LGNd X- or Y-cells can be preferentially influenced. The percentage of each cell type will be determined with electrophysiological techniques and each cell's sensitivity to spatial and temporal aspects of visual stimuli will be determined by measuring contrast sensitivity functions. Second, monocular deprivation will be used to create competitive effects on visual system development. Post-critical-period enucleation of the non-deprived eye will be performed to reveal remaining functional connections between geniculate cells and the visual cortex. Experiments will be conducted to determine the extent that the X- and/or Y-pathways are involved in these connections. And third, behavioral studies measuring spatial and temporal contrast sensitivity functions in cats experiencing the various types of visual restriction mentioned above will be conducted. The behavioral experiments will help to establish a correlation between physiological mechanisms, i.e., X- and Y-pathways, and behavioral capacity.